§ 402. Declaration of policy. It is hereby declared to be the policy of this state that any municipality acquiring, constructing, reconstructing, improving, bettering or extending an undertaking pursuant to this article shall manage such undertaking in the most efficient manner consistent with sound economy and public advantage to the end that the services of the undertaking shall be furnished at the lowest possible cost. No municipality shall operate such undertaking primarily as a source of revenue to the municipality, but shall operate such undertaking for the use and benefit of those served by such undertaking and for the promotion of the welfare and for the improvement of the health, safety, comfort and convenience of the inhabitants of the municipality.